Kinetic modular machine for producing energy from fluid flows

ABSTRACT

A kinetic modular machine for producing electricity from flows, either mono or bi-directional, moving at different speeds, includes one or more turbines that are “open center” and coaxial; a floating/positioning system; and a connection between the kinetic modular machine and a docking. Each turbine has a rotor, a stator, and a synchronous generator. In different configurations, the turbines are structurally, mechanically and electrically independent. The floating/positioning system includes a floater, a wing, and a fixture linking the turbines to the floater, implementing the control of the rotational axes (roll, pitch, yaw), with the wing keeping the machine at a given distance from the shore and the fluid surface. The modular design, having independent turbines, allows for a flexible design, keeping the installation and maintenance costs low.

TECHNICAL FIELD

The present invention concerns the turbines or fluid kinetic floatingturbines systems with a single and/or double rotor “open center”(without central shaft and/or hub), in other words the turbines equippedwith a floater positioning system, capable to produce electricity fromfluid flows, either one or bi directional one, operating at differentcurrent speeds.

In particular, the invention involves the turbine, the floating androtational (around the yaw, roll and pitch axes) system, the machineposition with respect to the shore and the flow.

BACKGROUND ART

As known, it is possible to build SintEnergy's turbines for producingelectricity from tidal streams. They consist of some kinetic machineswith mobile component parts allowing to produce energy full immersed inwater and moored to the shore by means of a rope subjected only to atensil stress driven by a rigid rode (on shore technology). The workingprinciple is quite similar to a kite: the machine is in equilibrium inthe water and doesn't change the position during the operation; it isalso able to self control its position even when the flow direction andintensity changes, maintaining the rotational plan perpendicular to theflow.

Such a SintEnergy turbine is designed as open center and consists of twocounter rotating coaxial rotors, of a single stator (unibody statorsolution), two synchronous, independent, built in generators, a centralwing (also named positioning wing), installed on the center of thestator, and a floater (buoy).

Each generator consists of two steel rings, one built in to the rotor(rotor steel ring) and the second to the stator (stator steel ring).These rings respectively house the permanent magnets and the coils.

Both rotors, functionally constrained to the stator, are onlyelectrically fully independent. During the operations, when the flowshits the machine, both rotors run inside the stator, together with thegenerators, producing electricity. The rotation is allowed by a numberof balls, at a datum gaps among them, along some races made on theflanks of the rotors.

The floater and the central wing allow to partially manage, in anadaptative mode, the machine position with respect to the water surfaceand the shore.

A disadvantage of the cited conventional technology is the partialtransient management related to the startup of the machine and when achange of the flow direction occurs.

Particularly, the above solution, in the author's opinion, doesn't allowto fully manage the machine axes rotations (yaw, roll, pitch) implyingany potential fluctuations risky for the “in water” machine stabilityand equilibrium, as well as the energy production.

More potential troubles can come from:

-   -   the high component elements production costs due to the        necessity of complex manufacturing procedures and machines,        mainly for the unibody stator manufacturing;    -   the stop of the energy production even in case of planned        maintenance or unattended failure of just one rotor, due to the        fact that both rotors are functionally connected to the stator;    -   the use of low aspect central wing, with low aerodynamic        efficiency, due to the small central hole;    -   the high installation costs, the reduced available shipping ways        and manageability of the machine due to the length of the whole        anchoring system, as requested to stay off the boundary layer        (see S. Barbarelli, G. Florio, M. Amelio, N. M. Scornaienchi, A.        Cutrupi, G. Lo Zupone Transients analysis of a tidal currents        self-balancing kinetic turbine with floating stabilizer Applied        Energy 160 (2015) 715-727);    -   the high building complexity due to the central deflector,        implying a complex device allowing to turn the machine when a        flow direction change occurs;    -   the machine efficiency is reduced due to turbulences induced by        the central wing;    -   the low mechanical efficiency during in the operation position        (with the swept area in front of the flow) due to the balls        bearing, located on the flanks of the rotors: for this reason        each rotors weight affect the bearing so it works under cutting        loads, increasing the mechanical friction and the cut in speed        (the speed at which the machine starts producing energy) and,        consequently, reducing the produced energy.

For the above reasons it is necessary to find innovative solutions inorder to exceed the said limitations.

DISCLOSURE OF INVENTION

The present invention aims to exceed any previous limitations, alreadyknown (closest prior art) in the fluid kinetic machines mainly due tothe actual configuration.

The main objective of the present invention, as in the attached claims,is to build a kinetic machine, able to produce energy from fluid flowsconsisting of a component (module) made of one or more turbinesstructurally, mechanically and electrically independent, reciprocallyconnected with screwed systems or pressure/click fixtures, with a builtin synchronous generator, in order to reduce the stop of the machine andthe loss of energy production when a failure of one or more turbinesoccurs.

A second objective, depending on the first one, is to build a modularkinetic machine for the energy production from flow currents, assemblinga number of component parts, in order to make easier the assembly phases(reducing the number of phases) and off shore maintenance, consequentlyreducing the risks, the time and the costs of production and management.

A third objective, depending on the previous one, it to make a number ofcomponentized parts (modulus), different and “taylor made” depending onthe requirements such the site characteristics or the load.

A forth objective is to supply a machine with characteristics ofstructural, chemical/physical/mechanical strength ideal with respect tooperating environment, ensured by the shape and kind of made ofmaterials, diversified related to the specific purpose.

A fifth objective is the full and right position control of the machine,also during the transients, achievable by a location of the positioningwing outside the turbine and a suitable design and modelling of thefloater.

A sixth objective is to increase the produced energy reducing themechanical friction over the rotors.

A seventh objective is to optimize the produced energy taking inconsideration some comparative Computational Fluid Dynamic (CFD)results.

One more objective is to use, for manufacturing and assembly thiskinetic machine, all the assembly strategies, parts, manufacturing anddevices already known, ie but not the only ones, screws, holdfast(mechanical and electrical), terminal, joining the parts of each machineor between machines, or for the customer interface.

Based on this invention, the innovative fluid kinetic machine allows tobetter operate converting the the energy from fluid streams, like thetidal or rivers ones, resulting more efficient and profitable comparedto the actual technology state of the art, because it consist of:

-   -   one or more turbines, as well as electrically are also        structurally and mechanically independent making the machine        fully modular;    -   a floating/positioning system implementing the control of roll,        pitch and yaw as well as the position with respect of the shore        and water surface;    -   a central hole free of any encumbrance and designed following        the CFD results in order to optimize the energy production, to        reduce the wake consequences behind the turbine and also the        environmental impact.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an axonometric view displaying a machine as per invention;

FIG. 2 is an axonometric view of the external bladed turbine (T1), crosssectioned by a diametral plan perpendicular to the rotational plan;

FIG. 3 is an axonometric view of the internal bladed turbine (T2), crosssectioned by a diametral plan perpendicular to the rotational plan;

FIG. 4 is a side view of the floating/positioning system (F) of themachine;

FIG. 5 shows the more profitable purpose of anchoring of the theinvention compared to the previous art;

FIG. 6 is a frontal view of the double turbine as assembled;

FIG. 7 is an axonometric view of a version of a single turbine machine(M) as per invention;

FIG. 8 is an axonometric view of the generator (G1), cross sectioned bya diametral plan perpendicular to the rotational plan, built in theturbine (T1);

FIG. 9 is an axonometric view of the generator (G21), cross sectioned bya diametral plan perpendicular to the rotational plan, built in theturbine (T2).

BEST MODE FOR CARRYING OUT THE INVENTION

The following descriptions are the minimum instructions whose anexpertise person needs to build the machine, consequently any otherimprovements/modifications can be introduced without any preconceptionsto the subject of the subject of the innovation and without vary therelated field of protection as defined on the claims.

The machine of the finding, generically defined as (M) in FIG. 1, is afloating one, i.e. immersed in water, but not anchored to the shore bed,just connected to the shore by a system allowing to balance the dragexerted over the machine itself by the flow.

The machine (M) following the invention consists of two coaxial turbinescounter rotating, one with external blades (T1) and the other withinternal blades (T2); a floating/positioning system; a connection systembetween machine and shore (FIG. 5 shows the working principle).

The turbine (T1), as shown in FIG. 2, consists of a rotor (R1), a stator(S1) and a synchronous generator (G1).

The rotor (R1), round shaped, is composed of four rings (1 a, 1 b, 1 c,1 d). It rotates inside the stator (S1) housing over the externalperimeter the blades (5).

The blades (5), of suitable aerodynamic shape and section and at lowaspect ratio (less than two), are characterized by a tapered shape withroot chord larger or equal than the tip one. The connection blade-rotoris at section with the longer chord.

The stator (S1) is a case torus shaped assembled with four rings (2 a, 2b, 2 c, 2 d).

The generator (G1), shown in FIG. 8, consists of a metal support ring(14), housed inside the rotor (R1), where are installed a number ofpermanent magnets (15) and a metal support ring (16), housed inside thestator (S1), where are installed a number of copper coils (17), in thesame quantity as the magnets.

The quantity of the rotor blades, the magnets and coils can varydepending on the design purpose and specifications.

The rotation of the rotor (R1) inside the stator (S1) is provided bymeans of rotating elements (4) of spherical, cylindrical or othersuitable shape, order to reduce the mechanical friction between statorand rotor. Such elements, in variable quantity depending on the purposeand design specifications, run along circular races made partially onthe rotor, near to the blades root, and partially on the stator (asshown in FIG. 2); these elements are positioned at the same mutualsuitable distance by a spacer (3). As optional configuration, instead ofthe rotating elements, it is possible, depending on the purpose, it ispossible to introduce, or use at the same time, any other devices usingother physical phenomena (as example, but not the only one, the magneticlevitation), in order to reduce the friction.

The turbine (T2), as shown in FIG. 3, consists of a rotor (R2), a stator(S2) and a synchronous generator (G2).

The rotor (R2), round shaped, is composed of four rings (6 a, 6 b, 6 c,6 d). It rotates inside the stator (S2) housing in the internalperimeter the blades (10). It rotates inside the stator (S2) housing inthe internal perimeter the blades (10).

The blades (10), of suitable aerodynamic shape and section, arecharacterized by a tapered shape with root chord smaller or equal thanthe tip one. The connection blade-rotor is at section with the smallerchord.

The stator (S2) is a case torus shaped assembled with six rings (7 a, 7b, 7 c, 7 d, 7 e, 7 f).

The generator (G2), shown in FIG. 9, consists of a metal support ring(18), housed inside the rotor (R2), where are installed a number ofpermanent magnets (19) and a metal support ring (20), housed inside thestator (S2), where are installed a number of copper coils (21), in thesame quantity as the magnets.

The quantity of the rotor blades, the magnets and coils can varydepending on the design purpose and specifications.

The rotation of the rotor (R2) inside the stator (S2) is provided bymeans of rotating elements (9) of spherical, cylindrical or othersuitable shape, order to reduce the mechanical friction between statorand rotor. Such elements, in variable quantity depending on the purposeand design specifications, run along circular races made partially onthe rotor, near to the blades root, and partially on the stator (asshown in FIG. 3); these elements are positioned at the same mutualsuitable distance by a spacer (8). As optional configuration, instead ofthe rotating elements, it is possible, depending on the purpose, it ispossible to introduce, or use at the same time, any other devices usingother physical phenomena (as example, but not the only one, the magneticlevitation), in order to reduce the friction.

The floating/positioning system (F), as shown in FIG. 4, consists of afloater (11), a positioning wing (12) and a fixture (13) connecting themachine to the floater.

The synergic operation provided by the cited components (11) (12) and(13) allows to control the machine at the datum distance from the watersurface and shore, as per design requirements, as shown in FIG. 5.

In particular:

-   -   the floater (11), suitably designed and modelled, provides the        right depth of the machine and the stability during the        transients in order to optimize the energy production (see: S.        Barbarelli, G. Florio, M. Amelio, N. M. Scornaienchi, A.        Cutrupi, G. Lo Zupone Transients analysis of a tidal currents        self-balancing kinetic turbine with floating stabilizer Applied        Energy 160 (2015) 715-727);    -   the positioning wing (12) allows controlling the machine        position with regard to the shore (see: Barbarelli S., Amelio        M., Castiglione T., Florio G., Scornaienchi N. M., Cutrupi A.,        Lo Zupone G., Analysis of the equilibrium conditions of a double        rotor turbine prototype designed for the exploitation of the        tidal currents, Energy Conversion and Management, 2014, Vol. 87,        pp. 1124-1133—doi:10.1016/j.egypro.2014.11.1005);    -   the connecting fixture machine-floater (13) consists of one or        more beams, or any other support structure useful for the        purpose, and it is designed for providing the optimal machine        depth, at which the maximum suitable flow speed is achieved as        required from the design.

The innovative aspects of the present invention, compared to the closestprior art, are:

Modularity

Structural, mechanical and electrical turbine independency, allowing themachine to be fully modular, proves to be the machine itself moreprofitable in terms of components manufacturing and assembling and alsomaintenance. Mainly, the modularity concept provides a stop operationtime reduction, to pull out one or more fault turbines meanwhile theremaining ones can continue the production even in a lower quantity.

Floating/Positioning System

The floating/positioning system (F) covers the control of the roll,pitch and yaw of the machine (M), thanks to the configuration and theinnovative features of the system (F). Its configuration, as perinvention, is specifically favourable because, as shown in FIG. 1, themachine (M) acts as a pendulum hinged at roll axis A′ and pitch axis B′(depending on the considered oscillation plan); meanwhile the rotationalcontrol around the yaw axis C is performed by the floater (11) shape andby the fluid dynamics performances of the positioning wing (12). Inparticular:

-   -   the floater volume (11), due to the volume of the moved fluid by        the immersed machine, provides to avoid the machine sinks;        meanwhile, the shape, due to specific fluid dynamic requirements        as shown in figures only for example purpose, allows to maintain        the right machine position during the small oscillations around        the axes A′ and B′;    -   the positioning wing (12), located outside the turbine, can be        designed at higher aspect ratios (more than one), in order to        operate with higher positioning angles and linking machine-shore        fixture shorter, as shown in FIG. 5 (cfr. S. Barbarelli, G.        Florio, M. Amelio, N. M. Scornaienchi, A. Cutrupi, G. Lo Zupone        Transients analysis of a tidal currents self-balancing kinetic        turbine with floating stabilizer Applied Energy 160 (2015)        715-727);    -   the length “l” of the element (13), measured from the rotational        axis A of the turbine, fixes the oscillation period of the        machine, once known mass and momentum of inertia of the the        machine itself.

Central Hole

The optimal sizing of the central hole is based on a comparativeanalysis performed by CFD, referring to a conventional turbine “windlike”, with central hub, a turbine open center single rotor, as perinvention, and a double rotor turbine, as per invention, demonstratethat the last one is profitable in terms of energy production.

It is in fact known that the performances, in terms of energyproduction, depend, at same other factors, on the Power Coefficient Cpand the swept area S.

The results show that, by increasing the central hole diameter Di, asshown in FIG. 6, maintaining the external diameter De of the turbine(T1), an open center turbine provides a Cp higher than a “wind like”(with central hub). Anyway the energy production is lower, in the opencenter case, due to the fact that the swept area reduces when thecentral hole diameter increases.

A good settlement, between the advantages taken from the conventionaltechnology and the ones offered from the open center solution, followingthe obtained results, is provided adopting the open center solutioncombined with the double rotor configuration, taking the advantages ofsuitable energy production of the innovative technology (as shown inGiacomo Lo Zupone, Mario Amelio, Silvio Barbarelli, Gaetano Florio, NinoMichele Scornaienchi, Antonino Cutrupi LCOE evaluation for a tidalkinetic self balancing turbine: Case study and comparison Applied Energy185 (2017) 1292-1302), on the current invention is based.

Indeed, this solution allows to achieve, despite a lower swept area, anincrease of Cp and energy production compared to the ones of theconventional technology, with more economic advantages (as shown inGiacomo Lo Zupone, Mario Amelio, Silvio Barbarelli, Gaetano Florio, NinoMichele Scornaienchi, Antonino Cutrupi LCOE evaluation for a tidalkinetic self balancing turbine: Case study and comparison Applied Energy185 (2017) 1292-1302).

It is also known that the central hole solution reduces the fauna impactand, as demonstrated by the CFD results, the wake phenomena, behind themachine, are significantly reduced.

FIG. 7 depicts one more example of practical execution of the inventioninvolving the principle just displayed. A single turbine configurationis more performing, in terms of Power Coefficient Cp, compared to thedouble rotor configuration previously considered, and so it is aprofitable solution for low cost purposes and/or small users.

Such a solution is mostly profitable for some purposes requiring anumber of installed turbines on the same anchoring structure, includingfloating/positioning systems custom designed.

SEQUENCE LISTING PART OF THE DESCRIPTION

-   -   M machine    -   T1 turbine: external bladed    -   T2 turbine: internal bladed    -   F floating/positioning system    -   A turbine rotational axis    -   B turbine pitch axis    -   C yaw axis    -   A′ machine roll axis    -   B′ machine pitch axis    -   1 machine—floater lenght fixture    -   R1 rotor 1    -   1 a ring 1    -   1 b ring 2    -   1 c ring 3    -   1 d ring 4    -   S1 stator 1    -   2 a ring 1    -   2 b ring 2    -   2 c ring 3    -   2 d ring 4    -   3 balls spacer    -   4 balls    -   5 blades    -   G1 external bladed turbine generator    -   14 generator rotor ring    -   15 magnet    -   16 generator stator ring    -   17 coil    -   R2 rotor 2    -   6 a ring 1    -   6 b ring 2    -   6 c ring 3    -   6 d ring 4    -   S2 stator 2    -   7 a ring 1    -   7 b ring 2    -   7 c ring 3    -   7 d ring 4    -   7 e ring 5    -   7 f ring 6    -   8 balls spacer    -   9 balls    -   10 blades    -   G2 internal bladed turbine generator    -   18 generator rotor ring    -   19 magnet    -   20 generator stator ring    -   21 coil    -   11 floater    -   12 positioning wing    -   13 fixture link machine-floater    -   22 prior art    -   23 new finding subject of present invention    -   24 anchoring element length of prior art    -   25 anchoring element length of new finding    -   26 anchoring base    -   27 boundary layer    -   28 shore    -   Di internal turbine diameter    -   De external turbine diameter

The invention claimed is:
 1. A modular kinetic machine (M) for producingelectricity from fluid flows, the modular kinetic machine being adaptedto be floating, in a fluid, open center, with a swept area fullyimmersed and perpendicular to flow direction, comprising: a firstturbine and a second turbine, one with external blades and the otherwith internal blades, which are coaxial and counter rotating and thatare mechanically and electrically independent; the first turbinecomprises a first rotor, a first stator and a first synchronousgenerator, the second turbine comprises a second rotor, a second statorand a second synchronous generator, a floating/positioning controldevice, a connection system, wherein each turbine is structurally,mechanically, and electrically independent, wherein thefloating/positioning control device comprises at least a buoy, apositioning wing, and a fixture connecting the turbines to the buoy,wherein the buoy is configured to allow positioning of the modularkinetic machine in terms of optimal depth and stable transient mood; andwherein the positioning wing (12) is installed out of the turbine, inproximity to the buoy (11) and the buoy (11) is linked to the turbine byone or more beams (13) configured for linking, wherein the connectionsystem is between the buoy and the shore.
 2. The modular kinetic machine(M), according to the claim 1, wherein each rotor and stator compriseparts that are centered on a rotational axis of the modular kineticmachine.
 3. The modular kinetic machine (M), according to the claim 1,wherein a number of blades is a maximum number for the properfunctioning of the kinetic modular machine, so as to reduce a load foreach blade and allow using materials having a lower structural strengthand lower machine weight and costs.
 4. The modular kinetic machine (M),according to the claim 1, wherein the two turbines have a center holethat is designed using a Di/De (external diameter/center hole diameter)ratio to provide a maximum available energy production.